In some instances, it may be important for a network administrator to determine the topology an optical network. For example, it may be helpful for the network administrator to determine that an optical fiber connects a given port of one device in the optical network to a given port of another device in the optical network. Knowledge of the topology of the optical network may be helpful when establishing routes through the optical network, diagnosing and remedying problems in the optical network, and for performing other manual or automated network management tasks.
Several approaches have been suggested as ways of determining the topologies of optical networks. Some of these approaches rely on a device sending wavelength-modulated optical signals on various ports of the device. The wavelength-modulated optical signal sent on a given port of the sending device encodes information that identifies the sending device and the given port. If a device receives the modulated optical signal on a given port, the receiving device demodulates the optical signal and outputs a report message to a network management system (NMS). The report message indicates that an optical fiber connects the given port of the receiving device to the given port of the sending device. The NMS may use such messages to generate topology data for the optical network. While effective, this approach requires the receiving device to include hardware to demodulate the optical signal. Such hardware may be complex and expensive, and only available in systems where a sending device is able to encode information in a wavelength modulated signal.